<template>
  <el-select v-model="valueTitle" multiple :clearable="clearable" @clear="clearHandle"  @change="changeData">
    <el-input
      class="selectInput"
      :placeholder="placeholder"
      v-model="filterText">
    </el-input>

    <el-option :value="valueTitle" class="options">
      <el-tree  id="tree-option"
        show-checkbox
        ref="selectTree"
        :accordion="accordion"
        :data="options"
        :props="props"
        :node-key="props.value"
        :default-expanded-keys="defaultExpandedKey"
        :filter-node-method="filterNode"
        :check-strictly="true"
        highlight-current
        @check="handleNodeClick">
      </el-tree>
    </el-option>
  </el-select>
</template>

<script>
export default {
  name: 'el-tree-select',
  props: {
    /* 配置项 */
    props: {
      type: Object,
      default: () => {
        return {
          value: 'value', // ID字段名
          label: 'label', // 显示名称
          children: 'children' // 子级字段名
        }
      }
    },
    /* 选项列表数据(树形结构的对象数组) */
    options: {
      type: Array,
      default: () => { return [] }
    },
    /* 初始值 */
    value: {
      type: String,
      default: () => { return null }
    },
    /* 可清空选项 */
    clearable: {
      type: Boolean,
      default: () => { return true }
    },
    /* 自动收起 */
    accordion: {
      type: Boolean,
      default: () => { return false }
    },
    placeholder: {
      type: String,
      default: () => { return '检索关键字' }
    }
  },
  data() {
    return {
      filterText: '',
      valueId: this.value, // 初始值
      valueTitle: [],
      defaultExpandedKey: []
    }
  },
  mounted() {
    this.initHandle()
  },
  methods: {
    // 初始化值
    initHandle() {
      if (this.value) {
        this.valueId = this.value.split(',')
      }
      this.initScroll()
    },
    // 初始化滚动条
    initScroll() {
      this.$nextTick(() => {
        const scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
        const scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
        scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
        scrollBar.forEach((ele) => { ele.style.width = 0 })
      })
    },
    // 切换选项
    handleNodeClick(node) {
      const res = this.$refs.selectTree.getCheckedNodes(false, true) // 这里两个true，1. 是否只是叶子节点 2. 是否包含半选节点（就是使得选择的时候不包含父节点）
      console.log('点击树形图获取当前选中的节点', res)
      // 这点要在外部定义 每次都是空的才不会重复
      const labelArr = []
      const valueArr = []
      const that = this
      res.forEach((element, index) => {
        labelArr.push(element[that.props.label])
        valueArr.push(element[that.props.value])
      })
      this.valueTitle = labelArr // 显示的
      this.valueId = valueArr // 发送给后端的数据
      if (this.valueId && this.valueId.length > 0) {
        this.$emit('getValue', this.valueId.toString())
      } else {
        this.$emit('getValue', null)
      }
    },
    changeData (e) {
      // 重新 设置tree
      this.$refs.selectTree.setCheckedKeys(this.valueId)
    },
    // 清除选中
    clearHandle() {
      this.valueTitle = []
      this.valueId = []
      this.defaultExpandedKey = []
      this.clearSelected()
      this.$emit('getValue', null)
      this.$refs.selectTree.setCheckedKeys(this.valueId)
    },
    /* 清空选中样式 */
    clearSelected() {
      const allNode = document.querySelectorAll('#tree-option .el-tree-node')
      allNode.forEach((element) => element.classList.remove('is-current'))
    },
    filterNode(value, data) {
      if (!value) return true;
      return data[this.props.label].indexOf(value) !== -1;
    }
  },
  watch: {
    value() {
      if (this.value) {
        this.valueId = this.value.split(',')
      } else {
        this.valueId = []
      }
    },
    options() {
      const that = this
      this.$nextTick(function() {
        if (that.valueId && that.valueId.length > 0) {
          that.$refs.selectTree.setCheckedKeys(this.valueId)
          const res = that.$refs.selectTree.getCheckedNodes(false, true) // 这里两个true，1. 是否只是叶子节点 2. 是否包含半选节点（就是使得选择的时候不包含父节点）
          const labelArr = []
          res.forEach((element, index) => {
            labelArr.push(element[that.props.label])
          })
          that.valueTitle = labelArr // 显示的
        }
      })
    },
    filterText(val) {
      this.$refs.selectTree.filter(val);
    }
  }
};
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
  .el-scrollbar .el-scrollbar__view .el-select-dropdown__item{
    height: auto;
    max-height: 274px;
    padding: 0;
    overflow: hidden;
    overflow-y: auto;
  }
  .el-select-dropdown__item.selected{
    font-weight: normal;
  }
  ul li >>>.el-tree .el-tree-node__content{
    height:auto;
    padding: 0 20px;
  }
  .el-tree-node__label{
    font-weight: normal;
  }
  .el-tree >>>.is-current .el-tree-node__label{
    color: #409EFF;
    font-weight: 700;
  }
  .el-tree >>>.is-current .el-tree-node__children .el-tree-node__label{
    color:#606266;
    font-weight: normal;
  }
  .selectInput{
    padding: 0 5px;
    box-sizing: border-box;
  }
</style>
